engleski

Exploring the effect of mutations on interactions between Keap1 and DPP III by MD simulations

Dipeptidyl peptidase III (DPP III) is a zinc- exopeptidase that cleaves dipeptides from the N-termini of short (3-10 amino acid) peptides. It cleaves bioactive peptides, such as angiotensin, Leu-enkephalin and Met-enkephalin, in vitro. In addition to its catalytic activity, it was discovered that it can affect the antioxidant response gene expression through the interaction with Keap1 protein, and consequential release of NRF2 transcription factor from the complex with Keap1. Keap1 acts as a substrate adapter protein for the E3 ubiquitin ligase complex, targeting the NRF2 for ubiquitination and degradation by the proteasome, which represses its transcriptional activity. Keap1 binds a specific "ETGE" motif of NRF2. Since DPP III also contains the "ETGE" motif, it competes for the same binding site in Kelch domain of Keap1, therefore displacing NRF2 and increasing its activity. Since the constitutively activated antioxidative response is involved in the development of resistance to anti-cancer treatments in cancer cells, this interaction has been given a lot of attention. The large-scale cancer genomics data offer insights into mutations found in cancer cells, which can help predicting possible 'functional' mutations in DPP III and Keap1, potentially responsible for the variations in their interaction affinity. In this work, molecular dynamics (MD) simulations were used to study how the point mutations influence properties of protein complexes comparing to the wild type. Following fluctuations and conformational changes in DPP III-Keap1 complexes during MD simulations, we obtained valuable insight into interaction mechanism on molecular level. This can be used for narrowing down the list of mutation candidates to be further studied by experimental methods.

Interactions, Keap1, DPP III, mutations

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